Plasma assisted molecular beam epitaxy of GaN with growth rates > 2.6 [mu]m/h

Plasma-assisted molecular beam epitaxial (PAMBE) growth of gallium nitride (GaN) was explored with a novel modification of a commercially available nitrogen plasma source. The modified nitrogen plasma source enabled a dramatic increase in the flux of active nitrogen and thus a significantly higher growth rate than has been previously reported. GaN films were grown using N sub(2) gas flow rates between 1 and 8 sccm while varying the plasma source's RF forward power from 200 to 600 W. The highest growth rate, and therefore the highest active nitrogen flux achieved was ~2.65 [mu]m/h. For optimized growth conditions the surfaces displayed a clear step-terrace structure with an average RMS roughness (3 [mu]m x 3 [mu]m) on the order of 1 nm. Secondary ion mass spectroscopy (SIMS) impurity analysis demonstrates oxygen and hydrogen incorporation of 1 x 10 super(16) and 5 x 10 super(16) respectively, comparable to the metal organic chemical vapor deposition (MOCVD) grown template layer. Initial un-optimized electron mobility measurements of 1 [mu]m thick GaN layers have shown a peak mobility of ~705 cm super(2)/V s for an electron concentration of ~3.5 x 10 super(16)cm super(-3). A revised universal growth diagram is proposed allowing the rapid determination of the metal flux needed to grow in a specific growth regime for any and all active nitrogen fluxes available.